Swiss diplomats negotiating with Iran on behalf of the United States for the release of an American woman accused of espionage have hit another road block: This time in the form of cash -- $500,000 to be exact -- that Iranian officials have demanded as the woman's bail.

It's the latest dip in an emotional roller coaster for the family of 32-year-old Sarah Shourd that began in earnest last Thursday when top Iranian officials, including President Mahmoud Ahmadinejad, announced that Shourd would be released Sept. 11. There was no mention of bail. Officials in Iran's judiciary canceled those plans Friday, but reinstated them Sunday with the bail requirement, according to an Iranian prosecutor who spoke to Iran's IRNA news agency.

Ever since, Shourd, who has spent 14 months in captivity in Iran, has been waiting in the wings as Swiss officials work to pull together the cash to buy her freedom. A senior U.S. official familiar with the negotiations told ABC News that the U.S. government would not be contributing any cash for Shourd's release.

An attorney for the Americans, Masoud Shafie, told ABC News Shourd could be released today, right up until midnight in Tehran, should the bail money be paid.

Shourd was detained along with her traveling companions, fiance Shane Bauer and friend Josh Fattal, in July 2009, when the trio of hikers was picked up after allegedly crossing into Iran from Iraq and imprisoned under accusations of espionage. No formal charges have been filed and the mothers of the hikers claim that if they entered Iran at all, they did so by accident.

Conditions of Shourd's bail do not prevent her from leaving Iran, but she would still face trial for allegedly illegally crossing Iran's border, along with Bauer and Fattal, who will remain in Iranian custody, according to Iranian prosecutor Abbas Jafari Dowlatabadi.

"I think it's irrelevant whether they actually believe they have a case or not," Rudi Bakhtiar of the International Campaign for Human Rights in Iran told "Good Morning America." "I think what's important is they are going to push that case... It would make them seem weak if they turn around and say, at this point, 'Hey, we've been mistaken.'"

Shourd's release was inspired at least in part by her deteriorating health -- a condition Shafie said he made clear to Iranian officials days before her release was first announced. Shourd has a serious gynecological condition, and has found a potentially cancerous lump in her breast.

"I gave a letter to Tehran investigators, and I warned [them] about Sarah's situation, and that her health is very weak. They can hold them for up to a year for the investigation, but not more than a year if they haven't been given a proper trial," Shafie told ABC News through a translator last week.

Shafie met with the hikers this weekend -- for the first time since they were detained -- and told ABC News they were in high spirits.

Iranian experts saw in the delay signs of a political split in Tehran's leadership.

ILNA, the news agency that reported the delay, is the news outlet the most critical of Ahmadinejad, and his political opponents don't seem to like the president's apparent attempt to turn Shourd's release into a public relations boost before next week's United Nations General Assembly.

"Sarah has become victim of political bickering in the country. This shows how deep rifts are within conservative establishment," Hadi Ghaemi of the International Campaign for Human Rights in Iran told ABC News Saturday.

Sarah Shourd Has Spent Most of 14 Months in Solitary Confinement

On Aug. 10, the mothers of the hikers made another open plea to Iran's leaders, invoking the sacred time of Ramadan and Shourd's "serious medical condition."

"Sarah has a serious medical condition and we are gravely concerned for her physical and emotional welfare, for which Iran's leaders are responsible. We urgently call on the Iranian authorities to end her isolation and provide her with adequate care," the mothers said in a statement on a website dedicated to the hikers' release.

In an interview with "GMA" in May, Shourd's mother, Nora Shourd, said she wasn't sure what she would do when finally reunited with her daughter.

"I think I'm just going to say ridiculously silly things," Nora Shourd said. "'I'm so glad to see you, sweetie. How are you? I love you.' You know, just ordinary stuff."

At the time, Shourd's mother told "Good Morning America" she was worried about her daughter because Swiss officials had told her the young woman was depressed. At the same time, The Associated Press reported Shourd had a serious gynecological condition.

After the initial reunion with their mothers in May, the three hikers spoke to reporters and described their captivity.

Shourd, who spent a majority of her captivity alone, said the food was "good," and we have medical care, which is appreciated."

Bauer, 28, said the group had a "decent relationship" with the guards, and that "it's been civil."

Fattal, 28, said the officials eventually allowed the Americans to have books while in confinement.

"Once we started getting books that really helped the prison experience a lot," he said.

Jubilant Reaction to Release News, Before Offer Rescinded

When news of the release first broke Thursday, the hikers' mothers were cautiously jubilant and released a statement on Facebook.

"We have seen the news reports and are urgently seeking further information," the statement said. "We hope and pray that the reports are true and that this signals the end of all three of our children's long and difficult detention. Shane, Sarah and Josh are all innocent, and we continue to call for their immediate release, so that they can return home together and be reunited with our families."

Just minutes later, the administrator of the Facebook account, a "friend or family" of the hikers, commented on the post and said, "I AM PRAYING!!!! GOD - THANK YOU!!!"

An hour ago, the adminstrator made another post, this time about "longing for" the hikers' release "as we wait and wonder."